Anthony Shook

Subcortical encoding of sound is enhanced in bilinguals and relates to executive function advantages

Bilingualism profoundly affects the brain, yielding functional and structural changes in cortical regions dedicated to language processing and executive function [Crinion J, et al. (2006) Science 312:1537–1540; Kim KHS, et al. (1997) Nature 388:171–174]. Comparatively, musical training, another type of sensory enrichment, translates to expertise in cognitive processing and refined biological processing of sound in both cortical and subcortical structures. Therefore, we asked whether bilingualism can also promote experience-dependent plasticity in subcortical auditory processing. We found that adolescent bilinguals, listening to the speech syllable [da], encoded the stimulus more robustly than age-matched monolinguals. Specifically, bilinguals showed enhanced encoding of the fundamental frequency, a feature known to underlie pitch perception and grouping of auditory objects. This enhancement was associated with executive function advantages. Thus, through experience-related tuning of attention, the bilingual auditory system becomes highly efficient in automatically processing sound. This study provides biological evidence for system-wide neural plasticity in auditory experts that facilitates a tight coupling of sensory and cognitive functions.

CLEARPOND: Cross-Linguistic Easy-Access Resource for Phonological and Orthographic Neighborhood Densities

Past research has demonstrated cross-linguistic, cross-modal, and task-dependent differences in neighborhood density effects, indicating a need to control for neighborhood variables when developing and interpreting research on language processing. The goals of the present paper are two-fold: (1) to introduce CLEARPOND (Cross-Linguistic Easy-Access Resource for Phonological and Orthographic Neighborhood Densities), a centralized database of phonological and orthographic neighborhood information, both within and between languages, for five commonly-studied languages: Dutch, English, French, German, and Spanish; and (2) to show how CLEARPOND can be used to compare general properties of phonological and orthographic neighborhoods across languages. CLEARPOND allows researchers to input a word or list of words and obtain phonological and orthographic neighbors, neighborhood densities, mean neighborhood frequencies, word lengths by number of phonemes and graphemes, and spoken-word frequencies. Neighbors can be defined by substitution, deletion, and/or addition, and the database can be queried separately along each metric or summed across all three. Neighborhood values can be obtained both within and across languages, and outputs can optionally be restricted to neighbors of higher frequency. To enable researchers to more quickly and easily develop stimuli, CLEARPOND can also be searched by features, generating lists of words that meet precise criteria, such as a specific range of neighborhood sizes, lexical frequencies, and/or word lengths. CLEARPOND is freely-available to researchers and the public as a searchable, online database and for download at http://clearpond.northwestern.edu.

The Bilingual Language Interaction Network for Comprehension of Speech.

During speech comprehension, bilinguals co-activate both of their languages, resulting in cross-linguistic interaction at various levels of processing. This interaction has important consequences for both the structure of the language system and the mechanisms by which the system processes spoken language. Using computational modeling, we can examine how cross-linguistic interaction affects language processing in a controlled, simulated environment. Here we present a connectionist model of bilingual language processing, the Bilingual Language Interaction Network for Comprehension of Speech (BLINCS), wherein interconnected levels of processing are created using dynamic, self-organizing maps. BLINCS can account for a variety of psycholinguistic phenomena, including cross-linguistic interaction at and across multiple levels of processing, cognate facilitation effects, and audio-visual integration during speech comprehension. The model also provides a way to separate two languages without requiring a global language-identification system. We conclude that BLINCS serves as a promising new model of bilingual spoken language comprehension.

Bilingual Two-Way Immersion Programs Benefit Academic Achievement

The effects of bilingual education on reading and math achievement were examined by comparing test scores across different elementary school programs. Results revealed that bilingual Two-Way Immersion (TWI) programs benefited both minority-language and majority-language students. Minority-language students in TWI programs outperformed their peers in Transitional Programs of Instruction, while majority-language students in Two-Way Immersion outperformed their peers in Mainstream monolingual classrooms. Bilingual Two-Way Immersion programs may enhance reading and math skills in both minority-language and majority-language elementary school children.

Bilingualism and inhibitory control influence statistical learning of novel word forms.

We examined the influence of bilingual experience and inhibitory control on the ability to learn a novel language. Using a statistical learning paradigm, participants learned words in two novel languages that were based on the International Morse Code. First, participants listened to a continuous stream of words in a Morse code language to test their ability to segment words from continuous speech. Since Morse code does not overlap in form with natural languages, interference from known languages was minimized. Next, participants listened to another Morse code language composed of new words that conflicted with the first Morse code language. Interference in this second language was high due to conflict between languages and due to the presence of two colliding cues (compressed pauses between words and statistical regularities) that competed to define word boundaries. Results suggest that bilingual experience can improve word learning when interference from other languages is low, while inhibitory control ability can improve word learning when interference from other languages is high. We conclude that the ability to extract novel words from continuous speech is a skill that is affected both by linguistic factors, such as bilingual experience, and by cognitive abilities, such as inhibitory control.

Parallel language activation and inhibitory control in bimodal bilinguals.

Findings from recent studies suggest that spoken-language bilinguals engage nonlinguistic inhibitory control mechanisms to resolve cross-linguistic competition during auditory word recognition. Bilingual advantages in inhibitory control might stem from the need to resolve perceptual competition between similar-sounding words both within and between their two languages. If so, these advantages should be lessened or eliminated when there is no perceptual competition between two languages. The present study investigated the extent of inhibitory control recruitment during bilingual language comprehension by examining associations between language co-activation and nonlinguistic inhibitory control abilities in bimodal bilinguals, whose two languages do not perceptually compete. Cross-linguistic distractor activation was identified in the visual world paradigm, and correlated significantly with performance on a nonlinguistic spatial Stroop task within a group of 27 hearing ASL-English bilinguals. Smaller Stroop effects (indexing more efficient inhibition) were associated with reduced co-activation of ASL signs during the early stages of auditory word recognition. These results suggest that inhibitory control in auditory word recognition is not limited to resolving perceptual linguistic competition in phonological input, but is also used to moderate competition that originates at the lexico-semantic level.

Bilingualism and Musicianship Enhance Cognitive Control

Learning how to speak a second language (i.e., becoming a bilingual) and learning how to play a musical instrument (i.e., becoming a musician) are both thought to increase executive control through experience-dependent plasticity. However, evidence supporting this effect is mixed for bilingualism and limited for musicianship. In addition, the combined effects of bilingualism and musicianship on executive control are unknown. To determine whether bilingualism, musicianship, and combined bilingualism and musicianship improve executive control, we tested 219 young adults belonging to one of four groups (bilinguals, musicians, bilingual musicians, and controls) on a nonlinguistic, nonmusical, visual-spatial Simon task that measured the ability to ignore an irrelevant and misinformative cue. Results revealed that bilinguals, musicians, and bilingual musicians showed an enhanced ability to ignore a distracting cue relative to controls, with similar levels of superior performance among bilinguals, musicians, and bilingual musicians. These results indicate that bilingualism and musicianship improve executive control and have implications for educational and rehabilitation programs that use music and foreign language instruction to boost cognitive performance.

Bilinguals Show Weaker Lexical Access during Spoken Sentence Comprehension.

When bilinguals process written language, they show delays in accessing lexical items relative to monolinguals. The present study investigated whether this effect extended to spoken language comprehension, examining the processing of sentences with either low or high semantic constraint in both first and second languages. English-German bilinguals, German-English bilinguals and English monolinguals listened for target words in spoken English sentences while their eye-movements were recorded. Bilinguals’ eye-movements reflected weaker lexical access relative to monolinguals; furthermore, the effect of semantic constraint differed across first versus second language processing. Specifically, English-native bilinguals showed fewer overall looks to target items, regardless of sentence constraint; German-native bilinguals activated target items more slowly and maintained target activation over a longer period of time in the low-constraint condition compared with monolinguals. No eye movements to cross-linguistic competitors were observed, suggesting that these lexical access disadvantages were present during bilingual spoken sentence comprehension even in the absence of overt interlingual competition.